Prime mover



1943- D. H. KILLEFFER 2,328,463

PRIME MOVER Original Filed Sept. 28, 1939 3 Sheets-Sheet 1 ATTORNEYS 1943- n. H. KILLEFFER 2,328,463

PRIME MOVER Original Filed Sept. 28, 1939 3 Sheets-Sheet 2 I150 L- i INVENTOR 55 ATTORNEYS Patented Aug. 31, 1943 PRIME MOVER David H. Killefier, Crcstwood, N. Y.

Original application Se ptember 28, 1939, Serial No. 296,874. Divided and this application June 16, 1942, Serial No. 447,235

7 Claims.

The present invention has for an object to provide an improved prime mover capable of operating effectively at relatively low pressure differentials.

The invention has been developed' more especially in connection with the design of a refrigeration unit wherein the effective refrigeration available from low temperature refrigerants is increased by interposing between the refrigerated space and the low temperature refrigerant, a prime mover which absorbs heat from the refrigerated space and converts part of it into work. For the purposes of disclosure such an em bodiment of the invention will be more particularly described as sufficiently illustrative.

The invention aims to provide an improved prime mover wherein the friction losses are reduced to a minimum.

Another object is to providea prime mover included in a closed system which when installed and adjusted can be hermetically sealed to prevent leakage and in which all moving parts are so enclosed within, the closed system that no moving parts extend through the walls thereof or require packing which permits movement.

Another object is to provide a prime mover wherein' a mobile liquid serves the function of a piston.

This application is a continuation in part of applicants co-pending application, Serial No. 747,548, filed Qcto er 9, 1934, now Patent No. 2,175,267 granted October 10, 1939, for Method of and apparatus for refrigeration, and it is a division of applicants co-pending application Serial No. 296,874, filed September 28, 1939, for Refrigerating systems.

The nature and objects of the invention will appear from a description of a particular embodiment thereof and an explanation of its operation for the purpose of which description and explanation reference should be had to the accompanying drawings forming a part hereof and in which- Figure l is a schematic drawing of a refrigerated chamber and accessory refrigerating apparatus,

Fig. 2 is a similar schematic drawing of the refrigerated chamber and accessory refrigerating apparatus of another embodiment,

Fig. 3 is a detail vertical section showing the operation of the liquid level valve control of the construction of Fig. 2, i

Fig. 4 is a vertical section taken on the line 4-4 of Fig. 3, I

Fig. 5 is a side elevation, with parts in section,

of the secondary refrigerating control elements of Fig.' 2,

Fig. 6 is a horizontal section taken substantially on the line 6-6 of Fig. 5,

Fig. 7 is a vertical section through the fluid pump taken substantially at right angles to Fig. 5 and substantially on the line 1-1 thereof.

For the purposes of illustrating the principles of the invention a refrigerating unit will be described wherein a low temperature refrigerant, such, for example, as solid carbon dioxide, commonly known as dry ice, is contained in a suitable receptacle and heat is extracted from the refrigerated chamber by mean of a low boiling point refrigerant of the type of ethyl chloride, including methyl chloride, dichloro-difluoromethane, iso-butane and others having the desired properties, which is evaporated by absorption of heat from the refrigerated chamber and then in turn is recondensed by delivering heat to the low temperature refrigerant. The refrigerant selected should preferably be one which will not solidify in the condenser, will have a substantial vapor pressure at the temperature of the refrigerated chamber but will not have too high a vapor pressure at room or shipping temperatures and will not be corrosive. A portion of the heat absorbed by the low boiling point refrigerant in the evaporator is expended in doing mechanical work and preferably this mechanical work is in turn utilized to provide additional refrigeration for the refrigerated space or for another refrigerated space, which may be maintained at a different temperature.

In the apparatus to be more particularly described a low temperature refrigerant is stored in a suitable receptacle and a low boiling point refrigerant is circulated between the low tem perature refrigerant by which it is condensed and the refrigerated chamber where it is vaporized by heat absorbed therefrom. A portion of the heat absorbed by circulating refrigerant is expended in operating a prime mover embodying the principles of the present invention. As shown the prime mover is connected to operate to provide further refrigeration. This secondary refrigerating circuit may operate in connection with the same or a different evaporator.

. Referring more principal outer insulating wall of a refrigerator is indicated at H] and an inner insulating wall ll forms a receptacle i2 for a low temperature refrigerant. Access to the chamber I 2 for recharging may be had through a suitable opening in the top. A refrigerated chamber I4 is cooled by an evaporator IS in which the low boiling point particularly to the drawings, a

refrigerant is vaporized as it absorbs heat from the refrigerated chamber.

The construction of the evaporator I5 may be substantially that of a radiator and if the exposed surface is sufficient the temperature within the refrigerated chamber will depend upon the boiling point of the low boiling point circulating refrigerant within the evaporator and, therefore, upon the refrigerant selected and the pressure within the evaporator. Control of the pressure,

.therefore, will control the temperature. The circulating refrigerant circulates between the evaporator |5 where it is evaporated and the condenser chamber |6 of the refrigerant receptacle |2 or at least in a position of heat exchange relation with the low temperature refrigerant. In accordance with a describedv embodiment of the invention provision is made for controlling the maximum pressure of the vapor as the circulating refrigerant is boiled in the evaporator, and therefore the temperature.

As shown in the drawings the flow of circulating refrigerant from the condenser I6 to the evaporator I5 is actuated by fluctuating pressure in the vertical tube i1. reduced refrigerant is withdrawn from the condenser past the check valve l8 into the tube H and when the pressure is again increased the refrigerant is forced through the check valve l9 and conduit into the evaporator. Tube I! is connected by conduit II to the region of fluctuating pressure in chamber 26.

Preferably the tube I1 is in contact with the wall of the condenser to keep the temperature thereof as low as possible.

The path of the vapor from the evaporator |5 to the condenser l6 includes a conduit to pump chamber or power chamber 26, vertical conduit 2'! to the chamber 28 and conduit 29 which leads to the condenser l6. A branch conduit 30 leads from the conduit 25 to the compressor or work chamber 3| and to cooling coil 32 and a return conduit 33 leads through the reducing valve 34 back to the inlet conduit 20 of the evaporator. The reducing valve may be of any usual type or it may even consist merely of a restricted orifice or nozzle.

Mercury movable to and fro between the power chamber .26 and the work chamber 3| acts as a working liquid and provides the pistons, in ef-- feet, for the chambers. The whole arrangement constitutes a prime mover deriving power from the vapor under pressure and a compressor arranged to compress vapor and, in the particular arrangement shown, to return the compressed vapor or liquid to the evaporator.

' The construction and operation of the apparatus will be understood from a consideration of Fig. 1. As the low boiling point refrigerant vaporizes in the evaporator l5, the vapor formed passes through the conduit 25 and tends to flow into the passage 35 formed in the L-shaped block 36 within the power chamber 26 and up to the valve seat 31 beneath the valve 39. The opening in the valve seat, however, is of small crosssectional area and the weight of the valve 39 is sufficient to hold back the vapor and prevent its passage. The valve opening should not be too small to permit the flow necessary for effective operation.

The vapor as it is formed, however, can flow from the conduit 25 through the branch conduit 36 to the compressor chamber 3| and it forces the mercury in this chamber up through the conduit 40 and into the power chamber 26. When When the pressure is the mercury rises in the chamber 26 sufficiently it lifts the valve 39 which will float on mercury from its seat 31 and the vapor flows into the chamber 26 from conduit 25. The valve shown is made of iron or steel to provide the necessary weight though floating readily on mercury. Whatever the material and the construction of the valve, it should be of such weight in proportion to the size of the aperture of the valve seat that it will effectively close and remain closed against the pressure of the vapor in the conduit 25 but it should be of such weight or otherwise so constructed that it will be lifted by the mercury or other working fluid as the same rises in the chamber 26; it is among'the advantages of the particular arrangement shown that all moving parts of the valve are entirely within the closed system with'no stuffing boxes or the like and in fact with no frictional moving joints yet perfect automatic control of inlet and outlet ports is attained.

As the vapor flows in, building up pressure in the chamber 26, the mercury will first now down through the tube 40 to the lower chamber 3| and compress refrigerant gas to force it under pressure into the condenser 32 but when the mercury falls below the point 4|, where the conduit 21 joins the conduit 46 further vapor flow and build up of pressure will force the short section or plug'of mercury in conduit 21 up into the chamber 28. The conduit 40 may be slightly restricted just below the chamber 26 as indicated at 44 if found desirable to improve the operation by inhibiting rapid now of the mercury and by reducing the tendency to force a large quantity of mercury up conduit 21. Check valves 42 and 43 at the inlet and outlet of the compressor chamber 3| insure the direction of flow. When the valve 39 is lifted by the mercury it engages the seat 45 formed on the lower end of the conduit 46 leading from the power chamber 26 to chamber 28 and as long as the pressure in the chamber 26 is substantially higher than in the V chamber 28, as is the case while the mercury is flowing down during its compressing action and until the slug of mercury in the conduit is forced up through the conduit 21, the valve 39 will be held against this seat to close this communication. The space between the top of the valve 39 and the seat 45 should be small in order that the valve may be sure to seat to close the outlet 46 immediately upon rising from the seat 31. In practice the desired result is not difficult to obtain because the vapor flowing in to the mercury through the valve seat 31 tends to raise the level of the mercury and thereby to increase the lifting force acting on the valve.

When the mercury has moved suificiently and vapor flows through the conduit 2! the pressure in the two chambers will be equalized and the valve will drop on to its seat 31, thus opening free communication through conduit 46. The mercury which asa slug in conduit 21 has moved into the upper chamber 28 now flows down through conduit 46 and if the valve 39 has not dropped will insure such action. The conduit 2! enters the chamber 28 horizontally and substantially tangent to the cylindrical wall, a feature which decreases spattering of the mercury and tends to delay somewhat the falling of the mercury onto the valve 39. This delay tends with other elements of the operation to permit a momentary blowing through of the vapor from the evaporator. From the point of view of increasing the circulation of refrigerant in its cycle this is advantageous. As permitting vapor to pass to the condenser without doing mechanical work, it is undesirable. In practice this and other phases of the operation must be adjusted to meet the requirements of the installation.

The length of the conduit 40 determines the weight of the column of mercury to be lifted in each movement and, therefore, the pressure that the vapor in the evaporator I and chamber 3| must attain to cause how of the mercury. Inasmuch as the pressure and temperature are inter-dependent functions of the particular liquid used as the low boiling point circulating refrigerant, the working temperature within the refrigerated chamber may be varied by changing the length of the column of mercury. Provision for such variation of the length of the column of mercury is indicated diagrammatically in the drawing, wherein telescoping joints 48 are shown as provided in the conduits to permit the chamber 3| to be moved vertically without disarranging the connections. A second possible position of the chamber 3| is indicated in dot and dash lines.

The length of conduit 21 determines the weight of mercury to be lifted by the vapor pressure in the power chamber 26 during the operation which equalizes pressure in the chambers 26 and 28 to permit the valve 39 to drop. Accordingly the working temperature within the refrigerated chamber may be varied by changing the length of this column of mercury. Telescoping joints 49 and an adjustable connection 29 make possible the adjustment. In short, the working temperature of the evaporator can be adjusted by adjustment of the effective length of either column. The effective length of the column not selected for control should be equal to or less than the length of the controlling column.

If the secondary refrigerating circuit includes its own separate evaporator either within the same refrigerated chamber or in another refrig erated chamber, the conditions and dimensions can be determined in accordance with the principles above outlined and others well understood.

It will be understood that the telescoping joints are shown more as than as a best practical construction. Actually the joints should be hermetically sealed as by welding to prevent any possible leakage, in operation after adjustment has been made at installation. An equivalent adjustment can be arranged by the use of connecting pipes that can be bent to change the relative level of one chamber.

The vapor passing from the evaporator I5 to the prime mover and compressor is ata temperature below the temperature of the refrigerated chamber whereas the power unit and compressor elements are, or may be, considerably warmer. For this reason it is desirable to provide suitable heat exchange units between conduits containing vapor, (or liquid if any) flowing in opposite directions. For this purpose a heat exchange unit 52 is provided between the conduit 25 carrying vapor from the evaporator I5 to the pump and conduit 29 carrying vapor from the chamber 28 to the condenser I6. Another heat exchange unit diagrammatically indicated at 53 is provided between the conduit 30, also carrying vapor from the evaporator I5 to the compressor and cooling coil 32 and the return conduit 33.

Whether the vapor is sufficiently condensed and cooled by the compressor and cooling coil 32 a diagrammatic illustration,

to reduce it to liquid condition, or not, it will be returned to the system through expansion valve 34.

It will be obvious upon analysis of the conditions existing in the described apparatus that the parts should be proportioned to obtain working conditions which are most suitable for a particular installation. For example the size of the evaporator I5 and of the condenser I6 should be suitably proportioned to the quantity of refrigerant so that suitable working levels of the refrigerant in either container will not be exceeded.

The capacity of the chambers 26 and 3| relative to the capacity of the evaporator should be selected in view of the preferred speed of operation of the prime mover and compressor and the proportion of the power available in the system which may effectively and profitably be used in doing work. The relative size of the power chamber 26 and of the evaporator I5 and the details of the mechanical arrangements will affect the quantity of vapor which blows through at the end of each operation. It would even be possible, if found desirable, to practically prevent the blow through of any substantial quantity of refrigerant vapor as, for example, by providing a U-shaped section at the top of the vertical conduit 27, so positioned that the slug of mercury which is forced from the conduit 2? up to the chamber 28 would be projected immediately into the conduit 46, thereby immediately closing the valve 39. Obviously this would change somewhat the operation of the arrangement shown wherein the conduit 21, chamber 28, and conduit 46 with associated parts constitute an automatic means for avoiding excessive pressure in the evaporator.

It will be obvious that the difference in level between the valve 39 and the work chamber or compressor chamber 3| should not be more than the length of the column of mercury which is effectively supported by the difference in vapor pressure between the refrigerant in the evaporator at the temperature to be maintained in the refrigerator chamber and the vapor pressure of the refrigerant in the condenser l6.

Another embodiment of the invention is illustrated in Figs. 2 to 7. The general arrangement -of this embodiment and in general the operation are the same as that in Fig. 1. The principal erator is indicated at H0 forms a receptacle H2 for frigerant. A refrigerated by an evaporator II 5. erant circulates between the condenser H6 within cle H2.

The flow of circulating refrigerant from the condenser I I6 is controlled by a float controlled valve H1, the float I I8 of which will rise in the condenser to open the valve when a sufficient quantity of liquid refrigerant is condensed within the condenser H6. When the valve H1 is opened the circulating refrigerant will flow through the conduit H9 to the reservoir I20 within the refrigerated chamber which reservoir is subject to the temperature of the refrigerated chamber. The outlet of this chamber may be controlled by a spring pressed valve I2I will be held closed when the pressure in the conduit I2I' leading to the evaporator H5 is surncient to hold back the column of liquid and will be released when the pressure is reduced during operation. An adjusting nut I22 may be proof the apparatus shown outer wall of a refrigand an inner wall III a low temperature rechamber H4 is cooled The circulating refrigthe evaporator I I5 and the refrigerant receptawhich vided to control the tension of the spring I23 of the check valve.

Various other arrangements may be made for feeding liquid refrigerant from the reservoir I20 into the circuit within the refrigerated chamber.

The vapor from th evaporator II flows to the condenser II6, through a conduit I25, power chamber I26, vertical conduit I21, the chamber I28 and conduit I29. A branch conduit I30 leads from the conduit I25 to the compressor chamber I3I and to cooling coil I32 and a return conduit I33 leads through nozzle I34 back to themlet conduit I2I of the evaporator.

The construction and operation of the vapor driven prime mover and compressor with connecting apparatus are similar in principle to that of the arrangement shown in Fig. 1. As the low boiling point refrigerant vaporizes in the evaporator II5, the vapor formed passes through the conduit I25 and tends to flow into the passage I35 formed in the L-shaped block. I36 within the chamber I26 and up to the valve seat I31 beneath the valve I39. The ball valve I39 holds back the vapor and prevents its passage.

The vapor as it is formed, however, can flow from the conduit I25 through the branch conduit I30 to the compressor chamber I3I and it forces the mercury in this chamber'up through the conduit I40 past the check valve MI and into the chamber I26. When the mercury rises in the chamber I26- sufficiently it lifts the valve I39 from its eat I31 and the vapor flows into the chamber I26 and by its pressure forces the mercury up through the conduit I21 and into the chamber I28. When the valve I39 is lifted by the mercury, it engaged the seat I45 formed on the lower end of the conduit I46 leading to chamber I28 and as long as the pressure in the chamber I26 is substantially higher than in the chamber I28 as is the case while the mercury is being forced up through the conduit I21 the valve I39 will be held against this seat to close this communication. The conduit I21 extends nearly to the bottom of the power chamber I26 and at its top enters the chamber I28 tangentially so that the flow of mercury into the chamber will involve as little spattering as possible for the reason that a spattering of the mercury into the outlet conduit I29 is objectionable for obvious reasons. The diameter of the conduit I21 is preferably relatively large so that when the mercury is discharged from the chamber I26 and the vapor follows the mercury up the conduit to the chamber I28 there will be little if any entrainment of mercury with the vapor.

When the mercury has been completely pumped and vapor flows through the conduit I21 the pressure in the two chambers will be equalized and the ball valve will drop on to its seat I31, thus opening free communication through conduit I46. The mercury which has been forced into the upper chamber I28 flows down through conduit I41 to compressor chamber I3I and compresses the vapor of the low boiling point refrigerant which has previously come from the evaporator II5 through conduits I25 and I30 and forces the compressed vapor into the cooling coil I32.

in the conduit I30 insure the direction of how. A check valve I50 may also be provided in conduit I41 if desired to prevent flow of mercury up the. conduit as the pressure fluctuates.

The length of the conduits I21 and I40 deter- Check valves I48 and I49 mines the weight of the column of mercury to be lifted in each movement and therefore the pressure that the vapor in the chamber I26, chamber I3I and evaporator II5 must attain to cause flow of the mercury. Inasmuch as the pressure and temperature are inter-dependent functions of the particular liquid used as the low boiling point circulating refrigerant, the temperature within the refrigerated chamber may be varied by changing the lengths of the columns of mercury and of the conduits. Provision for such variation of the length of the column of mercury is indicated diagrammatically in the drawings wherein the conduits I21, I40, I46, and I41 are shown as provided 'with telescoping joints to permit the chambers I28 and I3I to be moved vertically without disarranging the connections. A second possible position of the chamber I3I is indicated in dot and dash lines in Figure 2. As in the case of the structure shown in Fig. 1 the telescoping joints may be in fact welded when adjusted.

A heat exchange unit I52 is provided between the conduit I25 carrying vapor from the evaporator II5 to the power unit and conduit. I29 carrying vapor from the chamber I28 to the condenser II6. Another heat exchange unit I53 is provided between the conduit I30, also carrying vapor from the evaporator II5 to the compressor and cooling soil I32 and the return conduit I33.

Whether the vapor is sufficiently condensed and cooled by the compressor I3I and cooling coil I32 to reduce it to liquid condition, or not, it will be returned to the system through expansion valve at I34.

The float controlled valve H1 is shown more in detail in Fig. 3. The arrn I55 carrying the float H8 is pivoted at I56 ona fixed pivot. As the float lifts, a plunger I51 moves inwardly until it engages and lifts a ball valve I58 from the valve seat I59 against the tension of a spring I60. A spring I6I surrounding the plunger I51 urges the ball fromthe seat I59 and, therefore, when the valve once moved to open position it is held there permitting flow of the liquid refrigerant a little longer than might otherwise be the case. Tension of the springs I60 and I6I is, of course, adjusted to attain the results desired.

The power unit and compressor unit have been described as accomplishing their particular function in the refrigerator system herein described. This description is illustrative merely and is not intended as defining the limits of the invention. This unit is a prime mover capable of many uses not only in refrigerator systems but in other situations where gas or vapor under pressure is available. The power unit described is particularly adapted for use where the gas or vapor under pressure is corrosive or otherwise destructive to packing glands of unusual types, or where the pressure available is relatively low so that it is difficult to pack joints such as are usually required in prime movers to prevent leakage of vapor, gas or air to or from the system and at the same time permit movement of parts without friction, but the system is in no sense limited to such uses. The principles of the invention can be applied to apparatus designed for use under varying conditions including conditions of high pressure. The prime mover described comprises a working liquid which conveniently may be mercury as shown with some advantages inherent in the use of mercury, but it may be any other suitable liquid.

In the arrangement shown the work chamber or compressor chamber of the system is far enough below the level of the power system to take advantage of the hydrostatic head in order to meet the requirements of compressing the vapor of the low boiling refrigerant and forcing it back into the evaporator from which it comes and from which the power for operating the prime mover is derived. With different requirements other arrangements would be made. The pressure in the work chamber will be equal to the pressure in the power chamber plus (algebraically) the difference in hydrostatic head of the column of mercury or other working liquid in the system and therefore may be adjusted to meet various requirements.

It is to be noted that the prime mover shown operates between the pressure in the evaporator and the pressure in the condenser as between higher and lower pressures but that although in the system described the lower pressure is a relatively high vacuum this is merely an incident to the particular system and in no sense indicates limitation as to the absolute pressures with which the power unit may be used. The requisite for power is a difference of pressures with substantially no limitation as to what the absolute pressure may be at the inlet port and exhaust ports of the power chamber.

I claim:

1. A prime mover comprising, in combination, a power chamber having an inlet port and an exhaust port, a work chamber, a working liquid in said chambers movable from one chamber to the other, a valve operated in response to flow of working liquid into the power chamber to close the exhaust port and open the inlet port of the power chamber.

2. A prime mover, as defined in claim 1, wherein the valve is floated on the working liquid to move it from inlet port closing position to exhaust port closing position.

3. A prime mover comprising, in combination, a power chamber having an upwardly open inlet port and a downwardly open exhaust port, mercury operating as a piston movable to and from said chamber, a valve controlling the inlet and exhaust ports, said valve being of a weight sufficient to close the inlet port against the pressure there obtaining and being capable of being lifted from said inlet port by flotation on the mercury and to engage and close the exhaust port.

parts of which are entirely within 4. A prime mover comprising, in combination, a power chamber having an upwardly open inlet port and an exhaust port mercury operating as a piston movable to and from said chamber, a valve controlling the inlet and exhaust ports, said Valve being of a weight suiiicient to close the inlet port against the pressure there obtaining and being capable of being lifted from said inlet port by flotation on the mercury.

5. A prime mover comprising, in combination,

a closed system including a power chamber having an inlet port and an exhaust port and a work chamber, a working liquid in said closed system movable to and fro between said chambers, and a valve, all moving parts of which are entirely within said closed system, controlling the inlet and exhaust ports alternately to open one port and close the other.

6. A prime mover comprising, in combination, a closed system including a power chamber having an inlet port and an exhaust port and a work chamber having an inlet port and an exhaust port, a working liquid in said system movable to and fro between said chambers, a valve all moving said closed system controlling the inlet and exhaust ports of the power chamber operating automatically in response to flow of working liquid into the power chamber to open the inlet port and close the exhaust port and operating automatically in response to flow of the working liquid from the power chamber to open the exhaust port and close the inlet port and means automatically controlling the inlet and exhaust ports of the work chamber.

7. A prime mover comprising, in combination, a power chamber having an inlet port and an exhaust port, a work chamber, mercury movable to and fro between said chambers, a valve normally resting by gravity on the inlet port and closing it but engageable with the exhaust port to close the same when lifted from the inlet port, said valve being of a weight to close the inlet port against the pressure there obtaining and capable of floating on mercury and positioned to be lifted from the inlet port to engage and close the exhaust port when mercury flows into the power chamber and means operative in responsive to movement of mercury from the power chamber for causing the valve to move from exhaust port closing position to inlet port closing position.

DAVID H. KIILEFFER. 

